Hi guys, its been a while...

 

I left my boat covered and under a metal building for about 8 months between late last year, and up until last week. I have property in other states that I have been working on visiting. 

 

I made the mistake of not having the boat plugged in the entire time. I came back to completely dead batteries of course. So dead, that one of my chargers would not even recognize the battery being connected. All 4 batteries were down to .5 Volts. 

 

I used a different charger, and charged them all back up, and then put them back on the onboard charger (Dual Pro 4 bank) and got them all charged up on there, and I have left it that way. 

 

What do you think the odds are that the batteries are degraded enough to only last half the time or so out on the water? I could typically get a day and and some change on a full charge. These batteries are 3 Decka 27s, and an Interstate DC cranking 31.

How old are the batteries?

 

You could try charging them and then do a load test to see if they're still good.  If they're less than 2 years old its worth trying to keep using them.  If they're 3+ years old, they may be shot.

Odds are 50/50 , right? Might work might not haha. I’ve done that many times and they usually come back to life 

The load test is a good idea, most auto parts stores have testers, worth asking.

9 minutes ago, gimruis said:

How old are the batteries?

 

You could try charging them and then do a load test to see if they're still good.  If they're less than 2 years old its worth trying to keep using them.  If they're 3+ years old, they may be shot.

I haven't checked the dates on the batteries specifically, but the boat is a 2021, so I would imagine they were newish when the boat was rigged.

Sorry to say but the damage happens pretty fast. Like mention above take then to a battery store and have them load tested.

Some battery chargers have a desulfate, or battery repair mode.  I don't know how well they work.  But if yours has one, it might be worth a shot.  But I wouldn't go out and buy a charger with that feature and expect it to fix any problems.  It's more of a Hail Mary type thing.  

I also know a redneck trick to breaking up that sulfate crud. Not recommended for safety purposes but I have used it successfully when in remote areas without battery stores 

1 minute ago, TnRiver46 said:

I also know a redneck trick to breaking up that sulfate crud. Not recommended for safety purposes but I have used it successfully when in remote areas without battery stores 

Why doesn’t this surprise me 😂😂😂😂

The Dual Pro charger has a "maintenance" mode once they are fully charged. I am hoping if I have them on there in that mode for a while, it may come around. 

 

I have no problem getting new batteries and putting them in, but if I can save or delay spending $800+ on batteries, I will for a little while. 

If you don’t want to bother going to an auto parts store to get your batteries tested just buy a tester.  I have this one and it has served me well.  Only $22.

 

https://www.harborfreight.com/100-amp-612v-battery-load-tester-61747.html

1 minute ago, Tennessee Boy said:

If you don’t want to bother going to an auto parts store

 

Taking batteries out and hauling them to a store to get load tested is a pain in the rear.  What I would usually do is stop at one when I had my boat with me.  An employee would come outside and do it on the spot right in the parking lot.

Would I need to disconnect the 36V setup so they can be tested individually? It makes sense if I have to do that, but just wanted to make sure before I do it!

Just an fyi, Maint mode is a low voltage charge, something like 13.5v, it’s purpose is to keep the batteries charged during long term storage.

 

Some chargers have an Equalize stage that one runs occasionally to equalize the charge of the cells and do some desulftion, if that’s a word. In my RV, the Equalization mode was kicked off manually, voltage came up to somewhere around 16.5 and would stay there for a number of hours. I would do this once or twice a year.

1 hour ago, TnRiver46 said:

I also know a redneck trick to breaking up that sulfate crud. Not recommended for safety purposes but I have used it successfully when in remote areas without battery stores 

 

110V straight to the terminals for a couple quick bursts?

@casts_by_fly pretty much. You can throw it around a little to loosen the crud , then hit it hard with lots of amps and it will boil that mess. I have one of those battery chargers on wheels that has a 220 amp setting I refer to as defibrillator mode

1 hour ago, TnRiver46 said:

@casts_by_fly pretty much. You can throw it around a little to loosen the crud , then hit it hard with lots of amps and it will boil that mess. I have one of those battery chargers on wheels that has a 220 amp setting I refer to as defibrillator mode

I actually thought about boiling them for a little while with one of those chargers. My buddy has one, but I went a different route obviously. 

 

I am going to try out the load tester, and see what it tells me.

1 minute ago, InfantryMP said:

I actually thought about boiling them for a little while with one of those chargers. 

I only recommend defibrillator mode if you are like me, stuck at a campground an hour away from a battery store 😂 

For a load test on the TM batteries you could turn it on spin the prop in a bucket of water 

Are they AGM batteries, or just regular flooded lead acid batteries?   If they're flooded check them with a hydrometer.  If the specific gravity is good in all the cells then they're still good.  

 

If they're AGM batteries I suspect they're still good.   My experience with (automotive) AGM batteries is if they accept a charge after being completely dead they're still good.  

3 hours ago, Woody B said:

Are they AGM batteries, or just regular flooded lead acid batteries?   If they're flooded check them with a hydrometer.  If the specific gravity is good in all the cells then they're still good.  

 

If they're AGM batteries I suspect they're still good.   My experience with (automotive) AGM batteries is if they accept a charge after being completely dead they're still good.  

They are not AGM. I am going to try a load test on them this weekend. I am going to let the onboard charger have at them for the rest of the week.